SCEC Award Number 21035 View PDF
Proposal Category Collaborative Proposal (Data Gathering and Products)
Proposal Title Time-series InSAR analysis using ARIA standardized InSAR products in support of the Community Geodetic Model
Name Organization
David Bekaert National Aeronautics and Space Administration Gareth Funning University of California, Riverside
Other Participants Subcontract or JPL graduate-level internship for Simran Sangha from UCLA
SCEC Priorities 1a, 2a, 3e SCEC Groups Geodesy, SDOT, CXM
Report Due Date 03/15/2022 Date Report Submitted 04/01/2022
Project Abstract
The goal of the project was to densify and extend the California archive of standardized interferogram products available through the JPL ARIA project, and to use these to extend our InSAR time series covering southern California beyond the 2019 Ridgecrest earthquake sequence (July 4-5, 2019). These products and time series are intended as contributions to the SCEC Community Geodetic Model (CGM). To facilitate the production of a combined CGM deformation product, we developed methods to align and reference these time series to GNSS displacement time series across the SCEC-defined region, and to estimate and remove coseismic offsets due to the Ridgecrest earthquakes, to allow the extension of our time series estimates beyond July 2019. We made additional contributions to the CGM by testing a bootstrapping approach for estimating errors in both our estimated velocities and those from the consensus CGM velocities. We have also started to analyze our velocity data to demonstrate its utility for studying fault creep.
Intellectual Merit The development of methods to extend InSAR time series beyond major earthquakes is essential for building long-term time series of observations, and for estimating secular and short-term trends in deformation across the plate boundary system. The development of methods to assess the uncertainties in the consensus InSAR Community Geodetic Model will enable us to combine it with the GNSS CGM in a more rigorous manner. Understanding the distribution of aseismic slip on faults in Californai is a SCEC5 goal.
Broader Impacts As a community model, the CGM is an enabler of geophysical research into southern California in multiple ways - it will allow studies of strain accumulation on faults, of transient deformation, of crustal rheology; all of these can be used as inputs into next-generation models of seismic hazard, which will benefit society at large. The CGM will also be useful for other applications, such as measuring the deformation effects of groundwater use, drought and energy production. The majority of the work was conducted by an early career researcher of color.
Exemplary Figure Figure 4: Distribution of shallow creep on faults of central and southern California, as estimated from inverting profile offsets from our California-wide velocity data set. Filled squares are locations where profile fits were successful; positive values (red colors) indicate right-lateral creep rates, negative values (blue) indicate left-lateral creep rates. Hollow squares indicate sites with vertical rates in excess of geologic observations. We identify creep on the central San Andreas, Paicines, Superstition Hills, Imperial and Coachella San Andreas faults.